Noise-reducing valve construction
BACKGROUND OF THE INVENTION 
     The invention relates to a &#34;quiet-operating&#34; valve construction, as for use in conjunction with throttling elements of a reducing valve. The constructions disclosed in U.S. Pat. No. 4,921,014 are illustrative of one kind of valve to which the improvement of the present invention is applicable, and therefore the disclosure of said patent is hereby incorporated by reference. 
     In general, it may be said that a valve suitable for use in the present invention may comprise a radially stacked succession or nesting of concentric annuli, wherein a poppet member is guided in the bore of the innermost annulus. The annuli provide successive stages of circumferentially and axially distributed radial passages, with manifolding connection of plural passages of each stage to the next-succeeding stage; and, to serve the purposes of progressive pressure reduction, the total collective sectional area increases, for the passages of each successive stage. In a pressure-reducing application, poppet position determines the volume of inlet or upstream flow to be served by some or by all of the passages of the inner annulus, and the successive stages serve progressive fractions of desired pressure reduction. Outlet or downstream flow from the valve is taken via a circumferential manifold around the outermost multiple-passage annulus. 
     Despite the achievements of valve constructions according to said patent, there is a need for even further noise reduction and for more ready servicing, by disassembly for periodic cleaning to assure design flow capability of the passages of all stages. 
     BRIEF STATEMENT OF THE INVENTION 
     It is an object of the invention to provide an improved valve of the character indicated, and particularly adapted to small-scale construction. 
     Another object is to provide a noise-reducing mounting for a valve of the character indicated. 
     It is a specific object to meet the above objects with a construction wherein the valve itself is effectively compliantly suspended in a noise-containment envelope or casing. 
     Another specific object is to meet the above specific object by providing for selective adjustment of the compliant suspension. 
     A general object is to meet the above objects with a valve construction that incorporates superior sealing of connections between successive stages, while at the same time facilitating the disassembly and servicing of all components of the valve. 
     The invention achieves these objects by providing a two-part casing for the indicated multistage valve, wherein separable parts of the casing define a cavity for containing the nested stages of the valve. The cavity is cylindrical and has (i) axial-end wall surfaces that are spaced in excess of the axial length of the nested stages of the valve and (ii) a circumferential manifold surface in radial clearance with the plural radial passages of the outer tubular body member. Compliantly yieldable material is interposed between the respective end wall of the nested stages and the end-wall surfaces of the cavity, and the yieldable material is centrally open for accommodation of the poppet member. The casing provides an inlet-port connection to one end of the innermost bore of the nested stages, and the manifold surface of the casing has an outlet-port connection to the region of radial clearance. The two parts of the casing have such threaded engagement as to enable selective application of compressional load on the compliantly yieldable material. 
    
    
     DETAILED DESCRIPTION 
     The invention will be described in detail for preferred embodiments, in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a longitudinal section of a valve construction of the invention, drawn to enlarged scale; 
     FIG. 2 is a longitudinal section of the multiple-stage portion of the valve of FIG. 1; 
     FIG. 3 is an exploded isometric view of components of the multiple-stage portion of FIG. 2; 
     FIG. 4 is a view similar to FIG. 2, to show a modification; and 
     FIG. 5 is an exploded isometric view, as in FIG. 3 but specific to the modification of FIG. 4. 
    
    
     In FIG. 1, a concentrically nested array 10 of multiple stages of pressure-reducing passages is seen to be suspended within a relatively massive containment casing which consists of a cup-shaped casing part 11 and an annular closure part 12 having threaded reception at 13 to the skirt or open-end portion 14 of the casing part 11; continuous flow of pressure fluid is accommodated between a high-pressure inlet connection A and a reduced-pressure outlet connection B, all in accordance with current axially adjustable positioning of a poppet member P, as will become clear. The nested array 10 follows teachings of said patent and is seen in FIGS. 2 and 3 to comprise an inner tubular member 15 having a cylindrical poppet-guide bore 16, and plural further tubular members 17, 18 assembled thereto. All tubular members 15, 17, 18 are of the same axial length, so that the nested array has a cylindrical profile, with like circular end walls. 
     As shown, the inner tubular member 15 is characterized by like flanges 19, 19&#39; at the axial ends of a reduced cylindrical body surface 20, and plural axially spaced sets of passages 21 extend radially from bore 16 through to the body surface 20. The next successive tubular member 17 may be similarly formed on its outer body surface 22, between spaced end flanges 23, 23&#39;, but is shown further with an inner body surface 24 that is effectively recessed with respect to the radially inner portions of flanges 23, 23&#39;. As with the inner tubular member 15, the body of the next succeeding tubular member 17 has plural axially spaced sets of passages 25, extending radially through the body of member 17; the number of passages 25 exceeds the number of passages 21 through the body of member 15, whereby the total sectional area of passages 25 exceeds the total sectional area of passages 21. 
     At the respective axial ends of the nested array 10, confronting cylindrical lands of adjacent flanges 19/23 and 19&#39;/23&#39; have a slip-fit relation, whereby to facilitate assembly and disassembly, as for inspection, cleaning or other maintenance operations. 
     In similar fashion, the outer tubular member 18 has a recessed inner cylindrical body surface 26, between end-flange formation 27, 27&#39;, and plural axially spaced sets of passages 28 extend radially from body surface 26 to the outer cylindrical surface 29 of outer tubular member 18. Again, confronting cylindrical lands of adjacent flanges 23/27 and 23&#39;/27&#39; have a slip-fit relation for ease of assembly and disassembly, and the number of radial passages 28 through the body of outer tubular member 18 exceeds the number of radial passages 25 in tubular member 17. 
     The region 29 between slip-fitted lands at adjacent flanges 19/23 and 19&#39;/23&#39; defines a first circumferentially continuous annular manifold to receive a first-stage discharge of fluid flow through passages 21 of the inner tubular member 15, and to uniformly supply such first-stage discharge flow to the passages 25 of the next-succeeding stage 17. Similarly, the region 30 between slip-fitted lands at adjacent flanges 23/27 and 23&#39;/27&#39; defines a second circumferentially continuous annular manifold to receive a second-stage discharge of fluid flow through passages 25 of the second tubular member 17, and to uniformly supply such second-stage discharge flow to the passages 28 of the next-succeeding outer stage 18. The aggregate discharge of passages 29 is to another annular manifold, as will be later explained. 
     Description of the slip-fitted stage members 15, 17, 18 is completed by identifying axially open, circumferentially continuous grooves, as at 31, 32, 33, in the respective axial-end wall areas of members 15, 17, 18, for locating reception of an elastomeric O-ring (31&#39;, 32&#39;, 33&#39;) of appropriate size in each groove. The assembled array 10 is thus of right-cylindrical profile, except for the slight circumferentially continuous bulge of an O-ring in each of the grooves. 
     Returning now to FIG. 1, the casing parts 11, 12 are seen to define a generally cylindrical cavity in which the assembled array 10 is suspended, by and between relatively thick annular discs 35, 36 of compliant material, each of which is centrally open to conform to the diameter of bore 16 of the inner tubular member 15; the outer diameters of discs 35, 36 conform to the outer diameter of the assembled multi-stage array 10. In the case of disc 35, a central boss extends axially outward to locate an annular cap 37, and an elastomeric O-ring 38 is shown compressed between the outer land surface of cap 37 and the cylindrical wall of a short central recess in the bottom of the cupped cavity of casing part 11; disc 35 is further located in another and larger-diameter recess in the bottom of this cupped cavity. In the case of disc 36, an axially short counterbore in the face of a circular plate 40 establishes a circumferential lip 41 for location of disc 36. Plate 40 has a central poppet-guide bore 43 conforming to the diameter of the poppet-guide bore 16 of inner tubular member 15, and a tubular guide element 42 is shown integrally formed with plate 40, providing an axially outward extension of the guide bore 43 of plate 40. 
     A washer 44 is interposed between closure member 12 and plate 40, for uniformly distributed compressional squeezing action on the compliant discs 35, 36, upon threaded advance of closure member 12 into the otherwise-open end of casing part 11. 
     The poppet P is seen to comprise an elongate cylindrical portion 45 deriving piloting guidance from the bores 16 and 43, throughout controlled positioning displacement, pursuant to actuating force applied to an externally accessible portion 46 of the poppet. For the position shown in FIG. 1, the poppet has covered all passages of inner tubular member 15, thus closing the valve. But on sufficient downward displacement, the characterizing frustoconical valve-member portion 47 of the poppet begins to clear initially openable passages 21 of inner tubular member 15, thus beginning to open the valve to incoming flow from an inlet passage 48 in casing 11. After passing all stages of the array 10, fluid flow is received in another annular manifold 49, as determined by an internal circumferentially continuous contour of skirt 14, and with external-discharge porting formations 50 in skirt 14. 
     The casing 11, 12 and its multi-stage contents 10, with compliant discs 35, 36 and plate 40, will be seen as a unit-handling assembly, complete with an internal O-ring seal 52 of poppet P (to the guide-bore portion 53 of casing part 11), an internal O-ring seal 54 of poppet P (to the guide-bore portion 43 of plate 40 and its tubular extension), and a further internal O-ring seal 55 of plate 40 (to a smooth cylindrical bore portion of the skirt 14 of casing part 11). The compressional loading of discs 35, 36 on the O-ring seals at the end walls of the multi-stage array 10 is readily effected by torquing the threaded advance at 13, as by spanner access to diametrically opposed access bores 56 in closure part 12. And of course, an unthreading removal of closure part 12 from casing part 11 will release all parts for full disassembly, inspection, and servicing, as well as for later testing and calibration, in readiness for reinstallation, as in the bore 57 of larger structure 58 a fragmentary portion of which is shown in FIG. 1. 
     The larger structure 58 is seen to provide inlet-flow supply to the passage 48 of casing part 11, via a bore 59 from the inlet connection A to a circumferential manifold region 60, and the integrity of this path of inlet flow is assured by O-ring seals 61, 62 above and below the manifold region 60. In similar fashion, O-ring seals 62, 63 above and below another manifold region 64 assure integrity of discharge flow via ports 50 to the outlet connection B. 
     The array embodiment 10&#39; of FIGS. 4 and 5 will be seen to be identical to that of FIGS. 2 and 3, except for the placement and utilization of O-ring seals. Specifically, the O-ring seals in FIGS. 4 and 5 are located in radially outwardly open circumferential grooves 65, 66 in the respective convex cylindrical lands of the tubular members 15&#39; and 17&#39;, and these seals are designated with primed notation (65&#39;, 66&#39;) that is correlated with the identification of the grooves to which they are fitted. This being the configuration, it will be understood that, when the multi-stage array 10&#39; of FIGS. 4 and 5 is assembled to the casing 11, 12 of FIG. 1, the compliant discs 35, 36 fit continuously to the respective end areas of the assembled array, and in axially compressed loading, as determined by the threaded advance of closure 12 at 13. 
     As explained in U.S. Pat. No. 4,921,014, each of the radial passages of the respective tubular members is preferably configured as a frusto-conical diffuser, expanding from a radially inner entrance to a radially outer exit. Illustratively, this expansion may be 1:2 in diameter (1:4 in section area), as from 0.010-inch diameter to 0.020-inch diameter. These illustrative numbers apply for valve structure involving an array 10 or 10&#39; of as small as 3/16-inch outer diameter. 
     The compliant material at 35, 36 may be elastomeric, having a durometer of at least 90. Present experience has been satisfactory with products respectively known as Navydamp and Isodamp, being commercial products of EAR Division of Cabot Corporation, Indianapolis, Ind. 
     It is to be understood that the showings of three-stage devices 10, 10&#39; herein is purely illustrative, in that the number of stages will depend on the performance properties desired for particular applications.